4-Oxo-1-pyridinyl cephalosporin derivatives

ABSTRACT

Novel substituted(4-oxo-1-pyridinyl)acetylaminopenicillin and cephalosporin derivatives are prepared which are useful antibacterial agents.

CROSS-REFERENCES

This is a division of application Ser. No. 508,999, filed Sept. 27,1974, which is a continuation-in-part of application Ser. No. 413,565filed Nov. 7, 1973, now abandoned.

FIELD OF THE INVENTION

This invention relates to novel derivatives ofsubstituted(4-oxo-1-pyridinyl)acetylamino-penicillin and cephalosporins,to their methods of preparation, and to their usefulness asantibacterial agents.

BACKGROUND OF THE INVENTION

This invention relates to new synthetic compounds of the penicillin andcephalosporin classes which are useful as antibacterial agents. Thesecompounds possess a high degree of activity against a large number ofmicroorganisms. The cephalosporin derivatives of this invention areparticularly useful against penicillinase-producing microorganisms. Asantibacterial agents the compounds of this invention are therapeuticallyeffective in the treatment of infectious diseases due to gram-positiveand gram-negative bacteria in poultry and animals, including man. Inaddition, the compounds of this invention are useful as animal feedsupplements and as the active ingredient in germicidal preparationsemployed as surface disinfectants.

PRIOR ART

The cleavage of penicillins to 6-aminopenicillanic acid in 1959 and thechemical cleavage of cephalosporin to give the corresponding7-aminocephalosporanic acid made possible the synthesis of new syntheticpenicillins and cephalosporins not previously available via fermentationprocedures. Acylation of the amino group has produced derivativescontaining a heterocyclic ring in the 6-position side chain, as in thecase of the penicillin series, or in the corresponding 7-position sidechain, as in the case of the cephalosporin series. Such heterocyclesinclude the thiophene ring, as for example, U.S. Pat. Nos. 3,218,318,3,449,338 and 3,498,979 (cephaloridine and cephalothin); picoline, U.S.Pat. No. 3,553,203; hydantoin, U.S. Pat. No. 3,227,712; and variousother nitrogen containing heterocycles including pyrrolidine andnicotinic acid, U.S. Pat. No. 3,308,120.

In each instance the heterocyclic moity is attached to a side chain,generally that of an acetyl radical, via one of the ring carbon atoms.The present invention is concerned with 4-oxo-1-pyridinyl derivativeswhich are linked directly to the acetyl radical through the hetero atom.Examples known to applicants containing this type of linkage, and inthis regard representing the closest prior art, are the tetrazole ringin U.S. Pat. No. 3,516,997 (cefazolin) and certain quinazolinylderivatives of penicillanic acid, U.S. Pat. No. 3,652,547.

SUMMARY OF THE INVENTION

This invention relates to novel 4-oxo-1-pyridinyl penicillin andcephalosporin derivatives. More particularly, this invention relates tosubstituted(4-oxo-1-pyridinyl)acetylamino - penicillin and cephalosporinderivatives which are useful as antibacterial agents and which may berepresented by the general formula: ##STR1## wherein R₁, R₂, R₃ and R₄are each selected from the group consisting of hydrogen, halogen,hydroxyl, lower alkyl, trifluoromethyl, nitro, amino, cyano, carboxy,carbomethoxy, carbethoxy and when R₁ is taken in combination with R₂forms the cyclic radical --CH₂ CH₂ CH₂ CH₂ -- and --CH═CH--CH═CH--;

R₅ is selected from the group consisting of hydrogen, methyl, carboxy,carbomethoxy and carbethoxy;

R₆ is selected from the group ##STR2## X is selected from the groupconsisting of hydrogen, hydroxy, acetoxy, N-pyridinium,5-methyl-1,3,4-thiadiazol-2-ylthio and1-methyl-1,2,3,4-tetrazol-5-ylthio;

R₇ is selected from the group consisting of hydrogen, alkanoyloxymethyl,alkanoylaminomethyl, alkoxycarbonylaminomethyl and p-(alkanoyloxy)benzylin which the alkanoyl or alkoxy group contains from 1 to 5 carbon atoms;

R₈ is hydrogen or methoxy; and the pharmaceutically acceptable saltsthereof.

The compounds of the present invention are prepared by the condensationof a 6-aminopenicillanic acid or a 7-aminocephalosporanic acid with a(substituted)4-oxo-1-pyridinylacetic acid as illustrated in thefollowing reaction scheme. ##STR3##

DETAILED DESCRIPTION OF THE INVENTION

All of the compounds of the present invention contain a4-oxo-1-pyridinyl radical or a 4-pyridone moiety at the terminalposition of the acetylamino side chain, as indicated in general Formula(I) above. In the case of the penicillin series, the acetylamino sidechain is enumerated as the 6-position, whereas in the cephalosporinseries of compounds the 7-position is enumerated. The numbering systemfor these two series of compounds is illustrated for the intermediates6-aminopenicillanic acid (IV) and 7-aminocephalosporanic acid (V) below:##STR4##

The 4-pyridone moiety attached to the acetylamino side chain may besubstituted or unsubstituted. These substituents are present in eitherthe 2-, 3-, 5- or 6-positions of the pyridine nucleus and include thefollowing radicals: halogen, hydroxyl, lower alkyl, trifluoromethyl,nitro, amino, cyano, carboxyl and the methyl and ethyl esters of thecarboxyl radical. The term halogen includes the fluoro, chloro, bromoand iodo radicals. The term lower alkyl as used herein includes bothstraight and branched chain aliphatic hydrocarbon radicals having from 1to 4 carbon atoms. Specifically included are such members as methyl,ethyl, propyl, isopropyl, butyl, isobutyl, and the t-butyl radicals.

In addition to the various substituents described above, the 4-pyridonemoiety can be considered as substituted with an adjacent saturated orunsaturated six-membered ring. Thus, the symbol R₁ when taken incombination with the adjacent symbol R₂ can be viewed as forming anattached 6-membered alicyclic or aromatic derivative at the 2,3-positionof the pyridine ring. These derivatives are more properly termed2-[substituted(4-oxo-1-tetrahydroquinolinyl)]acetylamino and2-[substituted(4-oxo-1-quinolinyl)]acetylamino derivatives ofpenicillins and cephalosporins. Due to the symmetry of the pyridinemolecule only one pair of adjacent symbols need be so defined. Thepresent invention is not intended to include the tricyclic heterocyclicdibenzo-pyridine or acridine ring systems.

In addition to the mandatory substitution of the 2-methyl group of theacetylamino or acetamido portion of the molecule with 4-oxo-1-pyridinylradical, the 2-methyl group may contain additional substitution in theform of a methyl radical or a carboxyl radical as represented by thesymbol R₅. When R₅ is methyl, the compounds are more properly termed aspropionyl derivatives of 6-aminopenicillanic acid or of7-aminocephalosporanic acid. However, for the sake of uniformity innomenclature, they are termed as 2-(substituted)acetylamino derivativesherein. Thus, for example, in the case of a cephalosporanic acidderivative in which R₅ is methyl and the 4-pyidone remainsunsubstituted, the compound is designated as7-[2-(4-oxo-1-pyridyl)-2-methylacetylamino]cephalosporanic acid. Inaddition to the carboxyl radical at R₅ the methyl and ethyl esters orcarbomethoxy and carbethoxy radicals are also contemplated to be withinthe scope of the present invention.

This invention is essentially concerned with the preparation anddescription of 2-(4-oxo-1-pyridinyl)acetylamino side-chain derivativesof the β-lactam antibiotics. These derivatives are prepared bycondensation with the readily available 6-amino penicillanic acid or anyof the available 7-aminocephalosporin intermediates. Thus, where R₆ isthe radical ##STR5## derivatives of the penicillin series aredilineated, whereas when R₆ is the radical ##STR6## derivatives of thecephalosporin series are described.

The β-lactam nucleus can remain unsubstituted or it can be substitutedwith a methoxy substutuent as indicated by the symbol R₈. Suchsubstitution occurs at the 6-position of the penicillin series and atthe 7-position of the cephalosporin series of compounds.

Both the 3-position of the penicillin and the 2-position of thecephalosporin series of compounds are substituted by a carboxylic acidor a carboxylic acid ester as represented by the partial structure--COOR₇. When R₇ is hydrogen, the corresponding penicillanic acids orcephalosporanic acids are obtained. Additionally, the symbol R₇ canrepresent the following radicals: alkanoyloxymethyl,alkanoylaminomethyl, alkoxycarbonylaminomethyl andp-(alkanoyloxy)benzyl. These esters confer excellent properties ofabsorption upon the molecule and at the same time are physiologicallylabile. Thus, these esters are readily absorbed from thegastro-intestinal tract and enzymatically hydrolyzed to thecorresponding penicillanic or cephalosporanic acids thereby, providingexcellent oral activity.

Certain specific variations within the cephalosporin series are furtherindicated by the symbol X. Thus, where X is hydrogen thedesacetoxycephalosporanic acids are delineated; and where the symbol Xis hydroxyl, the desacetylcephalosporanic acids are indicated. Where thesymbol X represents an acetoxy radical the β-lactam nucleus is that ofcephalosporanic acid. Additional substituents at the 3-position ofdecephalosporanic acid which are included within the purview of thepresent invention and represented by the symbol X are the N-pyridinium,the 5-methyl-1,3,4-thiadiazol-2-ylthio and the1-methyl-1,2,3,4-tetrazol-5-ylthio radicals.

The pharmaceutically acceptable salts of the compounds of Formula (I)above include the non-toxic, carboxylic acid salts formed with anysuitable inorganic or organic bases. Illustratively, these salts includethose of alkali metals, as for example, sodium and potassium; alkalineearth metals, such as calcium and magnesium; light metals of Group IIIAincluding aluminum; and organic primary, secondary and tertiary amines,as for example, trialkylamines, including triethylamine, procaine,dibenzylamine, vinylamine, N,N'-dibenzylethylenediamine,dihydroabietylamine, N-(lower)alkylpiperidine, and additional amineswhich have been used to form non-toxic salts with benzylpenicillin.These salts can be prepared using conventional means such as contactingand neutralizing a solution of the carboxylic acid in a polar solventwith a stoichiometric quantity of a base.

Also included as pharmaceutically acceptable acid addition salts are thenon-toxic organic or inorganic acid addition salts of the base compoundsof Formula (I) above. Illustrative inorganic acids which form suitablesalts include hydrochloric, hydrobromic, sulfuric and phosphoric acidsas well as acid metal salts such as sodium monohydrogen orthophosphateand potassium hydrogen sulfate. Illustrative organic acids which formsuitable salts include mono, di and tricarboxylic acids, as for example,acetic, glycolic, lactic, pyruvic, malonic, succinic, glutaric, fumaric,malic, tartaric, citric, ascorbic, maleic, hydroxymaleic, benzoic,p-hydroxybenzoic, phenylacetic, cinnamic, salicylic, 2-phenoxybenzoicand sulfonic acids such as methane sulfonic acid and 2-hydroxyethanesulfonic acid. Such salts can exist in either a hydrated or asubstantially anhydrous form.

In addition to the non-toxic, carboxylic acid salts and the non-toxicacid addition salts of the base compounds, the term pharmaceuticallyacceptable salts is taken to include internal salts or zwitter-ions ofthose compounds of Formula (I) above which are amphoteric in nature.Thus, compounds such as7-[2-(4-oxo-1-pyridinium)acetylamino]cephalosporanate,7-[2-(4-oxo-1-pyridinium)acetylamino]-3-[(5-methyl-1,3,4-thiadiazole-2-ylthio)methyl]decephalosporanate7-[2-(4-oxo-1-pyridinyl)acetylamino](pyridiniummethyl)decephalosporanate,can exist as a dipolar ion, particularly when they are in solution.

Illustrative specific base compounds which are encompassed by Formula(I) above include:

6-[2-(4-oxo-1-pyridinyl)acetylamino]penicillanic acid,

6-[2-(2-hydroxy-4-oxo-1-pyridinyl)acetylamino]pencillanic acid,

6-[2-(3-trifluoromethyl-4-oxo-1-pyridinyl)-2-methylacetylamino]penicillanicacid,

6-[2-(2,3,5-trichloro-4-oxo-1-pyridinyl)acetylamino] penicillanic acid,

6-[2-(3-cyano-4-oxo-1-pyridinyl)acetylamino]penicillanic acid,

6-[2-(2-ethyl-5-methyl-4-oxo-1-pyridinyl)-2-carbethoxyacetylamino]penicillanicacid,

6-[2-(2-amino-4-oxo-1-quinolinyl)acetylamino]penicillanic acid,

acetoxymethyl 6-[2-(4-oxo-1-pyridinyl)acetylamino]penicillanate,

N-acetylaminomethyl 6-[2-(3-chloro-4-oxo-1-pyridinyl)acetylamino]penicillanate,

(N-ethoxycarbonyl-N-methyl)aminomethyl6-[2-(2-chloro-4-oxo-1-quinolinyl)acetylamino]penicillanate,

7-[2-(4-oxo-1-pyridinyl)acetylamino]cephalosporanic acid,

7-[2-(2-nitro-4-oxo-1-pyridinyl)acetylamino]cephalosporanic acid,

7-[2-(2,5-dicarboxy-4-oxo-1-pyridinyl)-2-carboxyacetylamino]cephalosporanicacid,

7-[2-(2-chloro-3-hydroxy-4-oxo-1-tetrahydroquinolinyl)acetylamino]cephalosporanicacid,

7-[2-(2,3,5,6-tetramethyl-4-oxo-1-pyridinyl)-2-methylacetylamino]cephalosporanicacid,

7-[2-(2,5-dicarbethoxy-4-oxo-1-pyridinyl)-2-carbethoxyacetylamino]cephalosporanicacid,

pivaloyloxymethyl 7-[2-(4-oxo-1-pyridinyl)acetylamino]cephalosporanate,

p-acetyloxybenzyl 7-[2-(3,5-dicyano-4-oxo-1-pyridinyl)acetylamino]cephalosporanate,

(N-propionyl-N-methyl)aminomethyl7-[2-(3-amino-4-oxo-1-pyridinyl)-2-carbethoxyacetylamino]cephalosporanate,

7-[2-(3,5-dimethyl-4-oxo-1-pyridinyl)-2-methylacetylamino]desacetoxycephalosporanicacid,

7-[2-(2-cyano-4-oxo-1-quinolinyl)acetylamino]desacetoxycephalosporanicacid,

7-[2-(2,3,5,6-tetraiodo-4-oxo-1-pyridinyl)acetylamino]desacetoxycephalosporanicacid,

7-[2-(2,6-dihydroxy-4-oxo-1-pyridinyl)-2-carbomethoxyacetylamino]desacetoxycephalosporanicacid,

7-[2-(2,6-dinitro-4-oxo-1-pyridinyl)acetylamino]desacetoxycephalosporanicacid,

7-[2-(4-oxo-1-pyridinyl)acetylamino]desacetylcephalosporanic acid,

7-[2-(2-carboxy-5-methyl-4-oxo-1-pyridinyl)-2-carboxyacetylamino]desacetylcephalosporanicacid,

7-[2-(3-amino-5-bromo-4-oxo-1-pyridinyl)acetylamino]desacetylcephalosporanicacid,

7-[2-(3-carbomethoxy-4-oxo-1-tetrahydroquinolinyl)-2-methylacetylamino]desacetylcephalosporanicacid,

7-[2-(3-trifluoromethyl-4-oxo-1-pyridinyl)acetylamino]desacetylcephalosporanicacid,

7-[2-(5-chloro-2-cyano-4-oxo-1-pyridinyl)acetylamino]desacetylcephalosporanicacid,

p-propionyloxybenzyl7-[2-(3,5-dichloro-4-oxo-1-pyridinyl)-2-carbomethoxyacetylamino]desacetylcephalosporanate,

isopropoxymethyl7-[2-(5-nitro-4-oxo-1-quinolinyl)acetylamino]desacetylcephalosporanate,

pivaloyloxymethyl7-[2-(4-oxo-1-tetrahydroquinolinyl)acetylamino]desacetoxycephalosporanate,

7-[2-(4-oxo-1-pyridinyl)acetylamino]-3-(pyridiniummethyl)decephalosporanate

7-[2-(2-hydroxy-3,5-dibromo-4-oxo-1-pyridinyl)acetylamino]-3-(pyridiniummethyl)decephalosporanate,

7-[2-(2,6-dicyano-4-oxo-1-pyridinyl)acetylamino]-3-(pyridiniummethyl)decephalosporanate,

7-[2-(2-carbomethoxy-4-oxo-1-pyridinyl)-2-carbethoxyacetylamino]-3-(pyridiniummethyl)decephalosporanate,

7-[2-(4-oxo-1-quinolinyl)acetylamino]-3-(pyridiniummethyl)decephalosporanate,

7-[2-(3-chloro-2,6-dimethyl-4-oxo-1-pyridinyl)-2-methylacetylamino]-3-(pyridiniummethyl)decephalosporanate,

7-[2-(4-oxo-1-pyridinyl)acetylamino]-3-[(5-methyl-1,3,4-thiadiazol-2-ylthio)methyl]decephalosporanicacid,

7-[2-(2-bromo-3,5-dichloro-4-oxo-1-pyridinyl)acetylamino]-3-[(5-methyl-1,3,4-thiadiazol-2-ylthio)methyl]decephalosporanicacid,

7-[2-(4-oxo-1-tetrahydroquinolinyl)-2-carboxyacetylamino]-3-[(5-methyl-1,3,4-thiadiazol-2-ylthio)methyl]decephalosporanicacid,

7-[2-(3-cyano-4-oxo-1-pyridinyl)-2-methylacetylamino]-3-[(5-methyl-1,3,4-thiadiazol-2-ylthio)methyl]decephalosporanicacid,

7-[2-(3,5-dihydroxy-4-oxo-1-pyridinyl)acetylamino]-3-[(5-methyl-1,3,4-thiadiazol-2-ylthio)methyl]decephalosporanicacid,

pivaloxymethyl7-[2-(4-oxo-1-pyridinyl)acetylamino]-3-[(5-methyl-1,3,4-thiadiazol-2-ylthio)methyl]decephalosporanate,

(N-ethoxycarbonyl-N-methyl)aminomethyl7-[2-(5-chloro-4-oxo-1-tetrahydroquinolinyl)-2-methylacetylamino]-3-[(5-methyl-1,3,4-thiadiazol-2-ylthio)methyl]decephalosporanate,

(N-acetyl-N-methyl)aminomethyl7-[2-(3-cyano-4-oxo-1-pyridinyl)acetylamino]-3-[(5-methyl-1,3,4-thiadiazol-2-ylthio)methyl]decephalosporanate,

7-[2-(4-oxo-1-pyridinyl)acetylamino]-3-[(1-methyl-1,2,3,4-tetrazol-5-ylthio)methyl]decephalosporanicacid,

7-[2-(5-methyl-2-propyl-4-oxo-1-pyridinyl)-2-methylacetylamino]-3-[(1-methyl-1,2,3,4-tetrazol-5-ylthio)methyl]decephalosporanicacid,

7-[2-(3-trifluoromethyl-4-oxo-1-pyridinyl)acetylamino]-3-[(1-methyl-1,2,3,4-tetrazol-5-ylthio)methyl]decephalosporanicacid,

7-[2-(4-oxo-1-quinolinyl)-2-carboxyacetylamino]-3-[(1-methyl-1,2,3,4-tetrazol-5-ylthio)methyl]decephalosporanicacid,

7-[2-(2-chloro-5,6-difluoro-4-oxo-1-pyridinyl)acetylamino]-3-[(1-methyl-1,2,3,4-tetrazol-5-ylthio)methyl]decephalosporanicacid,

acetoxymethyl7-[2-(4-oxo-1-pyridinyl)acetylamino]-3-[(1-methyl-1,2,3,4-tetrazol-5-ylthio)methyl]decephalosporanate,

(N-methoxycarbonyl-N-methyl)aminomethyl7-[2-(2,6-dihydroxy-4-oxo-1-pyridinyl)-2-carbethoxyacetylamino]-3-[(1-methyl-1,2,3,4-tetrazol-5-ylthio)methyl]decephalosporanate,

p-pivaloyloxybenzyl7-[2-(5-trifluoromethyl-4-oxo-1-quinolinyl)acetylamino]-3-[(1-methyl-1,2,3,4-tetrazol-5-ylthio)methyl]decephalosporanate,

7-methoxy-7-[2-(4-oxo-1-pyridinyl)acetylamino]cephalosporanic acid,

7-methoxy-7-[2-(4-oxo-1-pyridinyl)acetylamino]-3-[(5-methyl-1,3,4-thiadiazol-2-ylthio)methyl]decephalosporanicacid,

6-methoxy-6-[2-(4-oxo-1-pyridinyl)acetylamino]penicillanic acid,

7-methoxy-7-[2-(4-oxo-1-pyridinyl)acetylamino]decephalosporanic acid,

6-methoxy-6-[2-(3,5-dicyano-4-oxo-1-pyridinyl)acetylamino]penicillanicacid,

6-methoxy-6-[2-(5-nitro-4-oxo-1-quinolinyl)-2-carbethoxyacetylamino]penicillanicacid,

pivaloyloxymethyl6-methoxy-6-[2-(4-oxo-1-pyridinyl)acetylamino]penicillanate,

7-methoxy-7-[2-(5-chloro-4-oxo-1-quinolinyl)-2-methylacetylamino]cephalosporanicacid,

7-methoxy-7-[2-(2-hydroxy-4-oxo-1-pyridinyl)-2-carbomethoxyacetylamino]cephalosporanicacid,

acetoxymethyl7-methoxy-7-[2-(4-oxo-1-pyridinyl)acetylamino]cephalosporanate,

N-acetylaminomethyl7-methoxy-7-[2-(2,6-dimethyl-4-oxo-1-pyridinyl)-2-carbethoxyacetylamino]cephalosporanate,

7-methoxy-7-[2-(4-oxo-1-pyridinyl)acetylamino]desacetylcephalosporanicacid,

p-acetoxybenzyl7-methoxy-7-[2-(5-trifluoromethyl-4-oxo-1-quinolinyl)-2-ethylacetylamino]desacetoxycephalosporanate,

acetoxymethyl7-methoxy-7-[2-(4-oxo-1-pyridinyl)acetylamino]-3-[(5-methyl-1,3,4-thiadiazol-2-ylthio)methyl]decephalosporanate,

(N-ethoxycarbonyl-N-methyl)aminomethyl7-methoxy-7-[2-(4-oxo-1-pyridinyl)acetylamino]-3-[(1-methyl-1,2,3,4-tetrazol-5-ylthio)methyl]decephalosporanate,

The products of the present invention are prepared by reacting aβ-lactam 6-aminopenicillanic acid or 7-aminocephalosporanic acid, orderivative thereof, having the formula ##STR7## with a4-oxo-1-pyridinylacetic acid having the formula ##STR8## wherein thesymbols R₁, R₂, R₃, R₄, R₅, R₆ and R₈ have the values previouslyassigned.

The β-lactam starting materials (III) are all known compounds. Thecompound, 6-aminopenicillanic acid, having the formula ##STR9## can beprepared using biological methods and can also be prepared by thehydrolysis of various penicillins as described in U.S. Pat. No.3,499,909.

Hydrolysis of the antibiotic cephalosporin C results in the formation of7-aminocephalosporanic acid, Loder et al., Biochem. J. 79, 408-416(1961), having the formula ##STR10##

The compound 7-aminodesacetoxycephalosporanic acid having the formula##STR11## is prepared by the catalytic reduction of cephalosporin C,followed by the hydrolytic removal of the 5-aminoadipoyl side chain asdescribed in U.S. Pat. No. 3,129,224.

Those compounds of the β-lactam starting material (III) above whereinthe symbol R₈ represents a methoxy group have been previously describedin U.S. Pat. No. 3,778,432.

Treatment of cephalosporin C with an acetyl esterase prepared fromorange peel, Jeffery et al., Biochem. J., 81, 591 (1961) results in theformation of 3-hydroxymethyl-7-aminodecephalosporanic acid or7-aminodesacetylcephalosporanic acid having the formula ##STR12##

Treatment of cephalosporin C with pyridine followed by an acidhydrolysis produces the compound,7-amino-3-(pyridiniummethyl)decephalosporanic acid having the formulashown below. The preparation of this compound is known in the art anddescribed, for example, in U.S. Pat. No. 3,117,126 and British Pat. Nos.932,644, 957,570 and 959,054. ##STR13##

The 3-thiolated 7-aminocephalosporanic acids can be obtained by reacting7-aminocephalosporanic acid with the appropriate thiol as described inU.S. Pat. No. 3,516,997. Thus when 5-methyl-1,3,4-thiadiazole-2-thiol isemployed the compound7-amino-3-[(5-methyl-1,3,4-thiadiazol-2-ylthio)methyl]decephalosporanicacid is obtained, which has the formula ##STR14## When the compound1-methyl-1,2,3,4-tetrazole-5-thiol is employed the compound7-amino-3-[(1-methyl-1,2,3,4-tetrazol-5-ylthio)methyl]decephalosporanicacid is obtained having the formula

The 4-oxo-1-pyridinyl-(substituted)-acetic acids (II) used as startingmaterials are for the most part known compounds which can be synthesizedin either one or two steps via the condensation of an alkali metal saltof an hydroxypyridine (XI) with ethylbromoacetate or a substitutedethylbromoacetate (XII). Generally the potassium salt of hydroxypyridineis preferred to effect condensation, and the resulting ester hydrolyzedto the desired 4-oxo-1-pyridinyl-(substituted)-acetic acid (II) with anaqueous base as illustrated in the following reaction scheme: ##STR15##

Alternatively, the 4-oxo-1-pyridinyl-(substituted)acetic acids (II) aredirectly prepared by reaction of a 2-pyridone with chloroacetic acid ora substituted chloroacetic acid (XIV) in the presence of a strongaqueous base as indicated in the following reaction scheme: ##STR16## Apreferred method involves the prior silylation of a(substituted)-4-hydroxypyridine (XI) in the presence of an organic base,such as triethylamine, with a tri-(lower alkyl) substituted halosilane,as for example, chlorotrimethylsilane. This method enables purificationof the silylated intermediate which, in turn, results in the preparationof (substituted)-4-oxo-1-pyridinylacetic acids (II) having fewercontaminants and in an increased yield.

The (substituted)-4-oxo-1-pyridinyl acetic acids of Formula (II) whereinR₅ is hydrogen can also be prepared by treating pyrone or by treating asubstituted pyrone with glycine in the presence of a base. In thisnucleophilic reaction the pyrone ring is opened, water eliminated andthe ring reclosed with the amino nitrogen atom now contained in thepyridine ring. This reaction, which is generally conducted at elevatedtemperatures for an extended period of time, can be illustrated asfollows using 2,6-dimethyl-4-pyrone (XV) to prepare2,6-dimethyl-4-pyridone-1-acetic acid (XVI). ##STR17##

In general the 6-aminopenicillanic or 7-aminocephalosporanic acidderivatives of the present invention can be prepared by the condensationof a 4-oxo-1-pyridinylacetic acid (II) and an amino-β-lactam (III) aspreviously indicated. The coupling reaction is generally conducted insolution in the presence of a suitable solvent. Suitable solventsinclude acetone, dioxane, acetonitrile, chloroform, ethylene chloride,tetrahydrofuran or other inert and readily available solvents. Thecoupling reaction is further generally conducted in the presence of abase, such as an alkali metal carbonate or an alkali metal acidcarbonate, trialkylamine, in which the alkyl group has from 1 to 5carbon atoms or pyridine. The temperature of the coupling reaction canvary from -20° C. to 100° C. with the preferred temperature at roomtemperature or slightly below room temperature. The reaction time canvary anywhere from 15 minutes to as long as 36 hours, depending, ofcourse, upon the temperature of the reaction mixture and the reactivityof the particular reactants employed. Preferably a period of from 1 to 8hours is employed. Following the condensation reaction, the reactionproducts are isolated and recovered using conventional extraction andcrystallization procedures which are well known to those skilled in theart.

In order to provide a suitable driving force for the coupling reaction acoupling agent is employed. One type of coupling agent acts essentiallyas a dehydration agent, promoting the acylation and removing the waterformed during the reaction. Such dehydrative coupling agents ordehydration agents, as termed herein, include the compounds:dicyclohexylcarbodiimide, N-cyclohexyl-N-morpholinomethylcarbodiimide,pentamethylketone-N-cyclohexylimine,N-ethyl-5-phenylisoxazolium-3-sulfonate and phosphorous trichloride. Thecompound dicyclohexylcarbodiimide represents a preferred dehydrationagent particularly in the preparation of the cephalosporin series ofcompounds.

A second class of coupling agents can be viewed as interacting with thevarious 4-oxo-1-pyridinyl acetic acids employed in such a manner as toactivate the carbonyl radical of the acetic acid portion of themolecule, thereby forming a reactive intermediate. This reactiveintermediate, in turn, acylates the amino-β-lactam. Thus, thecorresponding acid halides, acid azides, mixed acid anhydrides withalkylphosphoric acid or alkylcarbonic acid, acid amides with imidazoleor a 4-substituted imidazole, acid cyanomethyl esters and acidp-nitrophenyl esters are all suitable reactive equivalents which may besuccessfully employed.

The preparation of a reactive intermediate represents a preferredprocess for the preparation of the compounds of this invention, and inparticular, for the preparation of the cephalosporin derivatives hereindescribed. Suitable coupling agents include carbonyldiimidazole,alkylchloroformate in which the alkyl group has from 1 to 5 carbonatoms, thionyl chloride, chloroacetonitrile, and bis-p-nitrophenylcarbonate. The preferred coupling agent is carbonyldiimidazole which, ingeneral, is added to a solution of the 4-oxo-1-pyridinylacetic acid at atemperature below room temperature. The reaction mixture is permitted toreach room temperature and the reaction mixture subjected to reducedpressure in order to remove the carbon dioxide evolved during theformation of the imidazolide. The solution containing the reactiveimidazolide intermediate is again chilled and now coupled with theappropriate β-lactam. Coupling is generally conducted at a temperatureof from 0° C. to 150° C. for a period of 1-12 hours, whereupon thedesired product is recovered using isolation techniques which are wellknown to those skilled in the art.

As an alternative to the direct coupling of the amino-β-lactam acid, theappropriate 6-aminopenicillanic acid or 7-aminocephalosporanic acid canbe coupled as a neutral salt or in the form of an ester. Suitable saltsinclude the trialkylammonium salts wherein the alkyl group has from 1 to5 carbon atoms. Illustrative of such salts are those formed withtrimethylamine or triethylamine. Esters represented by Formula (III)above are those in which the free carboxyl group of the amino-β-lactamhas been suitably esterified. In those cases in which the ester group issubsequently removed in order to obtain the free acid, a preference isshown for those ester groups which are readily removed.

Both the silyl and stannyl esters are among those esters readilyconverted to the corresponding free acid under relatively mildconditions. Thus, for example, the esters may be subjected tohydrolysis, solvolysis or a nucleophilic exchange, without alteration ofthe remaining portion of the molecule. Suitable silylating agentsinclude the alkyldisilazanes, as for example, tetramethyldisilazane andhexamethyldisilazane, or bis-trimethylsilylacetamide. Suitablestannylating agents include, for example, a bis-(tri-loweralkyl-tin)oxide such as bis-(tri-n-butyl-tin)oxide; a tri-loweralkyl-tin-hydroxide such as triethyl-tin-hydroxide; a tri-loweralkoxy-tin compound such as triethoxy-tin-hydroxide; and atri-lower-alkyl-tin-halide such as tri-n-butyl-tin-chloride. Theresulting silylated or stannylated carboxyl group can be regenerated tothe desired free carboxylic acid by treatment with a neutralhydrogen-donating agent. Water or a lower alkanol, as for example,ethanol, is preferably used as the hydrogen-donating agent.

An alternative method for the preparation of the compounds of thepresent invention involves the treatment of a 6α-haloacetamidopenicillinor a 7α-haloacetamidocephalosporin derivative with a silylated4-hydroxypyridine as illustrated in the following reaction scheme:##STR18## wherein R₁, R₂, R₃, R₄, R₅, R₆ and R₈ have the valuespreviously assigned; R₉ is lower alkyl having from 1 to 5 carbon atoms;and Y is bromo or chloro.

The α-haloacetamido-β-lactam starting materials are known compoundswhich have been previously described in J. Med. Chem. 16, 1413 (1973),Belgium Pat. No. 758,587, and U.S. Pat. Nos. 2,941,995 and 3,516,997.Preparation of the silylated 4-hydroxypyridines takes place with asuitable silylating agent as previously described. Suitable silylatingagents include: diloweralkyl chlorosilane, triloweralkyl chlorosilane,diloweralkyl bromosilane and triloweralkyl bromosilane in which theloweralkyl group contains from 1 to 5 carbon atoms,tetramethyldisilazane, hexamethyldisilazane andbis-trimethylsilylacetamide.

The condensation reaction is generally conducted in an inert solventsuch as chloroform, acetone, methylene chloride, dimethylformamidedioxane or acetonitrile. The temperature of the reaction can vary from-20° C. to 100° C. with a temperature of 20° C. preferred. Usually thereaction takes place in an inert atmosphere such as nitrogen, argon orhelium. The reaction is generally conducted for a period of from 15minutes to 36 hours, depending upon the nature of the reactants and thetemperature at which the reaction is conducted. The reaction is usuallycomplete in from 1 to 24 hours at the preferred temperature range.

In general, one equivalent of the silylated 4-hydroxypyridine derivativeis reacted with one equivalent of the α-haloacetamido-β-lactamderivative. The β-lactam derivative can also be employed in the form ofa salt, such as sodium, triethylamine, N,N-diethylaniline ordiisopropylethylamine. Alternatively, the β-lactam may be in the form ofan ester. Esters include those which can be readily removed toregenerate the free acid under mild conditions and which do not alterthe remainder of the molecule. Specifically, such esters include:t-butyl, trialkylsilyl and trialkylstannyl wherein the alkyl group hasfrom 1 to 5 carbon atoms or benzyl esters, with the preferred estersbeing of the trialkylsilyl type. Such esters can be readily hydrolyzedto the free acid by treatment with a neutral hydrogen donating agentsuch as an alcohol. In all of the aforementioned coupling reactions,compounds of the present invention having reactive functional groupswhich can interfere with the coupling reaction are protected usingsuitable blocking groups. Thus, carboxyl groups located on the4-pyridone portion of the molecule or on the acetic acid portion of themolecule may be silylated or etherified with other labile esters aspreviously described. Similarly, amino and hydroxyl groups located onthe 4-pyridone portion of the molecule can be suitably protected aslabile derivatives. Such derivatives include silyl ethers, benzyl ethersand carbonate esters for hydroxyl groups, carbobenzyloxy,carbo-t-butyloxy and triphenylmethyl derivatives for amino groups.

An alternative route to the cephalosporin derivatives of Formula (I),wherein the symbol X represents 5-methyl-1,3,4-thiadiazol-2-ylthio or1-methyl-1,2,3,4-tetrazol-5-ylthio, consists of the displacement of theacetoxy group from the methyl group at the 3-position of the substituted(4-oxo-1-pyridinylacetyl)aminocephalosporanic acids (XIX). This isillustrated in the following two reaction schemes: ##STR19## wherein thesymbols R₁, R₂, R₃, R₄, R₅ and R₈ have the values previously assigned.

The cephalosporanic acids of Formula (XIX) are dissolved with the2-mercapto-5-methyl-1,3,4-thiadiazole (XX) or a metallic salt thereof inan inert solvent. Preferably an alkali metal salt of the cephalosporanicacid (XIX) is employed. These salts can be prepared, for example, by thetreatment of the cephalosporanic acid with an alkali metal bicarbonate.The reaction is conducted in water or an aqueous organic solvent such asaqueous acetone, aqueous tetrahydrofuran or aqueous dimethylformamide.If desired, the pH of the reaction mixture can be controlled by theaddition of aqueous buffers. If the free cephalosporanic acids areemployed as starting materials, the reaction can be conducted in thepresence of a base, such as sodium bicarbonate, triethylamine, orpotassium bicarbonate.

The reaction can be conducted over a temperature range of from 25° C. to110° C. Preferably a temperature range of from 50° C. to 100° C. isemployed. If desired, the reaction may be conducted in the presence ofan inert gas such as nitrogen or argon. The reaction time may vary from15 minutes to 24 hours, with a reaction time of from 15 minutes to 6hours preferably employed.

In certain instances the displacement of the acetoxy group from themethyl group at the 3-position results in the migration of the doublebond to the 2-position of the β-lactam nucleus. Under thosecircumstances the position of the double bond can be re-established bythe oxidation of the ring sulfur to the sulfoxide with such oxidizingagents as a hydrogen peroxide, sodium metaperiodate or an organicperacid. Subsequent reduction of the sulfoxide by means of catalytichydrogenation or sodium dithionite provides the desired cephalosporinderivatives which are unsaturated in the 3-position of the β-lactamnucleus.

The novel compounds of the present invention are biologically active andhave been found to possess good antibacterial activity. Thus, they areuseful antimicrobial agents having a broad-spectrum of antimicrobialactivity in vitro against standard laboratory microorganisms which areused to screen activity against pathogenic bacteria. The antibacterialspectrum of typical compounds of the present invention is determined ina standard manner by the agar-dilution streakplate technique commonlyused for the testing of new antibiotics.

The presence of the 7-methoxy substituent in the cephalosporin serieshas a beneficial effect in increasing or enhancing the spectrum ofantimicrobial activity against certain gram-negative typemicroorganisms. More particularly, compounds containing the 7-methoxysubstituent are active against certain gram-negative microorganisms thatare resistant to compounds which do not contain the 7-methoxysubstituent, as for example, Enterobacter aerogenes, Enterobactercloacae, Serratia marcescens and the indole-positive species of Proteus.

The high in vitro antibacterial activity of the novel compounds of thisinvention not only makes them useful as pharmacological agents per se,but makes them useful as additives for animal feeds, as well asadditives for materials which are subject to microbial deterioration,such as cutting oils and fuel oils. These compounds are also useful fortheir antibacterial effect in soaps, shampoos and in topicalcompositions for the treatment of wounds and burns.

The invention described herein is more particularly illustrated inconjunction with the following specific examples.

EXAMPLE 1 4-Pyridone-1-acetic acid

A suspension of 4-hydroxypyridine (19.0 g., 0.2 mole), triethylamine(22.2 g., 0.22 mole) and toluene (300 ml.) is heated to its refluxtemperature and chlorotrimethylsilane (23 g., 0.2 mole) is addeddropwise. The mixture is heated with stirring at its reflux temperaturefor 18 hours and filtered. The filtrate is evaporated and the residue isdistilled at reduced pressure to yield 10.4 g. of silylated4-hydroxypyridine, b.p.₁₅ 102°-104° C.

The silylated 4-hydroxypyridine (9 g., 0.054 mole) is mixed withethylbromoacetate (25 ml.) and the mixture is stirred until theexothermic reaction subsides. The solidified mixture is triturated withether and filtered. The solid is recrystallized from isopropyl alcoholto give 8 g. of 4-pyridone-1-acetic acid, ethyl ester, hydrobromidesalt, having a m.p. of 195° C.

The ester, hydrobromide salt (8 g., 0.03 mole) prepared in this manneris added to a 1 N sodium hydroxide solution (80 ml) and the mixture isstirred for 5 hours, acidified and evaporated to 20 ml. The solution ischilled and filtered to yield 3.7 g of 4-pyridone-1-acetic acid having am.p. 265°-6° C.

Following essentially the same procedure but substituting3-methyl-4-pyridinol, 2,5-dimethyl-4-pyridinol, 3-nitro-4-pyridinol forthe 4-hydroxypyridine above, there is obtained3-methyl-4-pyridone-1-acetic acid, 2,5-dimethyl-4-pyridone-1-acetic acidand 3-nitro-4-pyridone-1-acetic acid, respectively.

EXAMPLE 2 4-Quinolone-1-acetic acid

4-Hydroxyquinoline trihydrate (20 g., 0.2 mole) is dissolved in a 50%aqueous potassium hydroxide solution and chloroacetic acid (20 g., 0.2mole) is incrementally added. The resulting solution is heated at itsreflux temperature for 18 hours, chilled, acidified and filtered to give7 g of 4-quinolone-1-acetic acid having a m.p. 278°-279° C.

Following essentially the same procedure but substituting3-cyano-2,6-dimethyl-4-pyridinol, 5-chloro-2-ethoxy-4-pyridinol or3-trifluoromethyl-4-pyridinol for the 4-hydroxyquinoline trihydrateabove, results in the preparation of3-cyano-2,6-dimethyl-4-pyridone-1-acetic acid,5-chloro-2-ethoxy-4-pyridone-1-acetic acid and3-trifluoromethyl-4-pyridone-1-acetic acid, respectively.

EXAMPLE 3 2,6-Dimethyl-4-pyridone-1-acetic acid

2,6-Dimethyl-4-pyrone (12.4 g., 0.1 mole) is added to a solution oftriethylamine (20 g., 0.2 mole) and glycine (7.5 g., 0.1 mole) inethanol (100 ml)/water (10 ml). The mixture is heated to its refluxtemperature for 4 days, chilled, acidified and filtered to yield 4 g of2,6-dimethyl-4-pyridone-1-acetic acid, having a m.p. of 243° C.

Following essentially the same procedure but substituting3-methyoxy-2-methyl-4-pyrone, 3-hydroxy-4-pyrone, and2,6-dicarbethoxy-4-pyrone for the 2,6-dimethyl-4-pyrone above, resultsin the formation of 3-methoxy-2-methyl-4-pyridone-1-acetic acid,3-hydroxy-4-pyridone-1-acetic acid and2,6-dicarbethoxy-4-pyridone-1-acetic acid, respectively.

EXAMPLE 4 7-[2-(4-Oxo-1-pyridinyl)acetylamino]cephalosporanic acid,sodium salt

The compound 4-pyridone-1-acetic acid (3.06 g., 0.02 mole) is dissolvedin dimethylformamide (50 ml) and the solution is chilled to 0° C.Carbonyldiimidazole (3.2 g., 0.02 mole) is added and the mixture isstirred under nitrogen at 0° C. for 30 minutes and then warmed to roomtemperature. The reaction flask is evacuated for 30 minutes to removethe carbon dioxide and chilled to -20° C. In a separate flask,7-aminocephalosporanic acid is silylated by heating a suspension of7-aminocephalosporanic acid (5.4 g., 0.02 mole) and hexamethyldisilazane(8 ml) in chloroform (50 ml) at reflux for 30 minutes. This solution isevaporated to dryness to remove the liberated ammonia. A solution of theresidue in chloroform (50ml) is chilled to -20° C. and added to theimidazolide. The reaction mixture is stirred at 0° C. for 1 hour, warmedto room temperature and stirred overnight.

The solution is treated with 2 ml of methanol and the precipitated7-aminocephalosporanic acid is removed by filtration. A solution ofsodium 2-ethylhexanoate in n-butanol (10 ml of a 2 N solution) is added,and the mixture is diluted with ether to an approximate volume of 1liter in order to precipitate the product. After reprecipitation frommethanol with ether, a yield of 2.2 g. of7-[2-(4-oxo-1-pyridinyl)acetylamino]cephalosporanic acid is obtained asa white solid having a m.p. of 180° C. (dec). Iodine titration indicateda purity of 72.7%.

Repeating essentially the same procedure but substituting6-aminopenicillanic acid, 7-aminodesacetylcephalosporanic acid,7-amino-3-[(5-methyl-1,3,4-thiadiazol-2-ylthio)methyl]decephalosporanicacid,7-amino-3-[(1-methyl-1,2,3,4-tetrazol-5-ylthio)methyl]decephalosporanicacid and 7-amino-7-methoxycephalosporanic acid for the7-aminocephalosporanic acid above, results in the formation of thesodium salt of 6-[2-(4-oxo-1-pyridinyl)acetylamino]penicillanic acid,7-[2-(4-oxo-1-pyridinyl)acetylamino]desacetylcephalosporanic acid,7-[2-(4-oxo-1-pyridinyl)acetylamino]-3-[(5-methyl-1,3,4-thiadiazol-2-ylthio)methyl]decephalosporanicacid,7-[2-(4-oxo-1-pyridinyl)acetylamino]-3-[(1-methyl-1,2,3,4-tetrazol-5-ylthio)methyl]decephalosporanicacid, and 7-methoxy-7-[2-(4-oxo-1-pyridinyl)acetylamino]-cephalosporanicacid, respectively.

EXAMPLE 5 6-[2-(4-Oxo-1-quinolinyl)acetylamino]-penicillanic acid,sodium salt

A solution of 4-quinolone-1-acetic acid (4.1 g., 0.02 mole) in 50 ml ofdimethylformamide is placed under an atmosphere of nitrogen, chilled to10° C. and carbonyldiimidazole (3.2 g., 0.02 mole) is added in oneportion. After the mixture has warmed to room temperature the flask isevacuated for 15 minutes to remove the carbon dioxide evolved information of the imidazolide. The solution is chilled to 10° C. and asolution of 6-aminopenicillanic acid (4.4 g., 0.02 mole) andtriethylamine (5 g., 20% excess) in chloroform (50 ml) is added. Thereaction mixture is stirred at 10° C. for 1 hour, warmed to roomtemperature and stirring is continued for an additional 3 hours.

Ten ml of a 2 N solution of sodium 2-ethylhexanoate in butanol is addedand the product is precipitated by the addition of ether (700 ml). The6-[2-(4-oxo-1-quinolinyl)acetylamino]penicillanic acid is filtered,reprecipitated from methanol with ether and vacuum dried to yield 4.8 gof a white solid, m.p. 204° C. (dec). Iodine titration indicates 86.4%purity.

Repeating essentially the same procedure, but substituting2,5-dimethyl-4-pyridone-1-acetic acid, 3-nitro-4-pyridone-1-acetic acid,3-hydroxy-4-pyridone-1-acetic acid and 3,5-diiodo-4-pyridone-1-aceticacid for the 4-quinolone-1-acetic acid above, results in the preparationof the sodium salt of6-[2-(2,5-dimethyl-4-oxo-1-pyridinyl)acetylamino]penicillanic acid,6-[2-(3-nitro-4-oxo-1-pyridinyl)acetylamino]penicillanic acid,6-[2-(3-hydroxy-4-oxo-1-pyridinyl)acetylamino]penicillanic acid and6-[2-(3,5-diiodo-4-oxo-1-pyridinyl)acetylamino]penicillanic acid,respectively.

Substituting 7-amino-7-methoxycephalosporanic acid for the 6-aminopenicillanic acid above results in the formation of the sodium salts of

6-[2-(4-oxo-1-quinolinyl)acetylamino]-7-methoxycephalosporanic acid,

6-[2-(2,5-dimethyl-4-oxo-1-pyridinyl)acetylamino]-7-methoxycephalosporanicacid,

6[2-(3-nitro-4-oxo-1-pyridinyl)acetylamino]-7-methoxycephalosporanicacid,

6-[2-(3-hydroxy-4-oxo-1-pyridinyl)acetylamino]-7-methoxycephalosporanicacid, and

6-[2-(3,5-diiodo-4oxo-1-pyridinyl)acetylamino]-7-methoxycephalosporanicacid.

EXAMPLE 67-[2-(2,6-Dimethyl-4-oxo-1-pyridinyl)acetylamino]-cephalosporanic acid,sodium salt

2,6-Dimethyl-4-pyridone-1-acetic acid (3.6 g., 0.02 mole) is dissolvedin dimethylformamide (50 ml.) and the solution is chilled to 0° C.Carbonyldiimidazole (3.2 g., 0.02 mole) is added and the mixture isstirred under nitrogen at 0° C. for 30 minutes and permitted to warn toroom temperature. The reaction flask is evacuated for 30 minutes toremove the evolved carbon dioxide. The resulting solution is chilled to-20° C. and a chloroform solution (50 ml.) oftrimethylsilyl-7-aminocephalosporanic acid (0.02 mole) prepared as inExample 4 above, is added thereto. The reaction mixture is stirred at 0°C. for 1 hour, warmed to room temperature and stirred overnight.

The reaction mixture is treated with 2 ml. of methanol and theprecipitated 7-aminocephalosporanic acid is removed by filtratration. A2 N solution of sodium 2-ethylhexanoate in n-butanol (10 ml.) is addedto the reaction mixture, which is diluted to 1 liter with ether andfiltered. The7-[2-(2,6-dimethyl-4-oxo-1-pyridinyl)acetylamino]cephalosporanic acid soobtained is reprecipitated from methanol using ether and vacuum dried toyield 5.0 g. of a white powder having a m.p. of 240° C.

Following essentially the same procedure but substituting3-methyl-4-pyridone-1-acetic acid,5,6,7,8-tetrahydro-4-quinolene-1-acetic acid,5-chloro-2-ethoxy-4-pyridone-1-acetic acid,3-trifluoromethyl-4-pyridone-1-acetic acid and3-hydroxy-4-pyridone-1acetic acid for the2,6-dimethyl-4-pyridone-1-acetic acid above results in the preparationof the sodium salts of7-[2-(3-methyl-4-oxo-1-pyridinyl)acetylamino]cephalosporanic acid,7-[2-(5,6,7,8-tetrahydro-4-oxo-1-quinolinyl)acetylamino]cephalosporanicacid,7-[2-(5-chloro-2-ethoxy-4-oxo-1-pyridinyl)acetylamino]cephalosporanicacid,7-[2-(3-trifluoromethyl-4-oxo-1-pyridinyl)acetylamino]cephalosporanicacid and 7-[2-(3-hydroxy-4-oxo-1-pyridinyl)acetylamino]cephalosporanicacid, respectively.

Substituting trimethylsilyl-6-amino-6-methoxypenicillanic acid for thetrimethylsilyl-7-aminocephalosporanic acid above results in theformation of the sodium salts of

6-[2-(2,6-dimethyl-4-oxo-1-pyridinyl)acetylamino]-6-methoxypenicillanicacid,

6-[2-(3-methyl-4-oxo-1-pyridinyl)acetylamino]-6-methoxypenicillanicacid,

6-[2-(5,6,7,8-tetrahydro-4-oxo-1-quinolinyl)acetylamino]-6-methoxypenicillanicacid,

6-[2-(5-chloro-2-ethoxy-4-oxo-1-pyridinyl)acetylamino]-6-methoxypenicillanicacid,

6-[2-(3-trifluoromethyl-2-oxo-1-pyridinyl)acetylamino]-6-methoxypenicillanicacid, and

6-[2-(3-hydroxy-4-oxo-1-pyridinyl)acetylamino]-6-methoxypenicillanicacid.

EXAMPLE 77-[2-(4-Oxo-1-pyridinyl)acetylamino]-3-(pyridiniummethyl)decephalosporanicacid

7-[2-(4-Oxo-1-pyridinyl)acetylamino]cephalosporanic acid, sodium salt,is dissolved in water and reacted with pyridine in the presence ofpotassium thiocyanate at 60° C. for 6 hours. Work-up is conductedaccording to J. L. Spencer, et al., J. Org. Chem. 32, 500 (1967) andresults in the preparation of7-[2-(4-oxo-1-pyridinyl)acetylamino]-3-(pyridiniummethyl)decephalosporanicacid as the zwitterion.

EXAMPLE 8 7-[2-(4-Oxo-1-pyridinyl)acetylamino]-desacetylcephalosporanicacid

7-[2-(4-Oxo-1-pyridinyl)acetylamino]cephalosporanic acid, sodium salt,is treated with an acetyl esterase isolated from orange peel accordingto J. D'A. Jeffery, et al., Biochem. J., 81, 591 (1961) to yield7-[2-(4-oxo-1-pyridinyl)acetylamino]desacetylcephalosporanic acid,sodium salt.

EXAMPLE 9 4-Trimethylsilyloxypyridine

To 500 g. of crude 4-hydroxypyridine is added 5.5 l. of toluene. Themixture is heated with stirring and approximately 700 ml. of toluene isdistilled in order to remove any water present. The reaction mixture ismaintained at its reflux temperature and trimethylsilylchoride (543 g.)is slowly added thereto. The reaction mixture is refluxed forapproximately 3 hours, cooled and filtered. The filtrate is evaporatedunder reduced pressure to remove the toluene and the residue distilledat 18-20 mm. yielding 620 g. of 4-trimethylsilyloxypyridine having ab.p. of 95°-6° C. at 18-20 mm.

EXAMPLE 10 7-[2-(4-Oxo-1-pyridinyl)acetylamino]cephalosporanic acid,sodium salt

To 20.0 g of 7-(2-bromoacetamido)cephalosporanic acid, prepared inaccordance with U.S. Pat. No. 3,647,789, is added 135 ml. of chloroformand 20 ml. of N,O-bis(trimethylsilyl)acetamide. The mixture is stirredfor about 1 hour under an atmosphere of dry nitrogen gas. 9.4 ml of4-trimethylsiloxypyridine added and the resulting mixture stirred atroom temperature for approximately 15 hours while maintaining anatmosphere of dry nitrogen gas. Methyl alcohol (80 ml.) is added to thereaction mixture with stirring until all of the precipitate whichinitially forms is dissolved. The mixture is poured into approximately 1liter of anhydrous ether with stirring, the solvent removed bydecantation, and the sticky precipitate which remains is dissolved in anadditional 400 ml. of methyl alcohol. A solution of 2 Nsodium-2-ethylhexanoate (65 ml.) in n-butanol is added to the solutioncontaining the dissolved precipitate, and the resulting mixture istreated with charcoal and filtered through a bed of diatomaceous earth.Isopropyl alcohol (900 ml.) is slowly added to the filtrate. Theprecipitate which forms is removed by filtration, washed with ether anddried in vacuo to yield 17.2 gms. of7-[2-(4-oxo-1-pyridinyl)acetylamino]-cephalosporanic acid, sodium salt.

Following essentially the same procedure and substituting7-[2-chloroacetamido]-7-methoxycephalosporanic acid,7-[2-chloro-2-methylacetamido]desacetylcephalosporanic acid,7-[2-bromo-2-carbethoxyacetamido]desacetoxycephalosporanic acid,6-[2-chloro-2-methylacetamido]penicillanic acid,6-[2-bromoacetamido]-6-methoxypenicillanic acid, and6-[2-bromo-2-carbethoxyacetamido]penicillanic acid for the7-(2-bromoacetamido)cephalosporanic acid above, results in thepreparation of7[2-(4-oxo-1-pyridinyl)acetylamino]-7-methoxycephalosporanic acid,7-[2-(4-oxo-1-pyridinyl)-2-methylacetylamimo]desacetylcephalosporanicacid,7-[2-(4-oxo-1-pyridinyl)-2-carbethoxyacetylamino]desacetoxycephalosporanicacid, 6-[2-(4-oxo-1-pyridinyl)-2-methylacetylamino]penicillanic acid,6-[2-(4oxo-1-pyridinyl)acetylamino]-6-methoxypenicillanic acid, and6-[2-(4-oxo-1-pyridinyl)-2-carbethoxyacetylamino]-penicillanic acid astheir sodium salts, respectively.

Substituting 2,6-dimethyl-4-trimethylsilyloxypyridine,2,6-bis(carbotrimethylsilyloxy)-4-trimethylsilyloxypyridine and3-chloro-4-trimethylsilyloxypyridine for the 4-trimethylsiloxypyridineabove results in the formation of the corresponding2-(2,6-dimethyl-4-oxo-1-pyridinyl), 2-(2,6-dicarboxy-4-oxo-1-pyridinyl),and 2-(3-chloro-4-oxo-1-pyridinyl) derivatives of the variouscephalosporanic and penicillanic acids shown as their sodium salts,respectively.

EXAMPLE 117-(α-Bromoacetylamino)-3-[(5-methyl-1,3,4-thiadiazol-2-ylthio)methyl]decephalosporanicacid

To 1.4 g. of7-amino-3-[(5-methyl-1,3,4-thiadiazol-2-ylthio)methyl]decephalosporanicacid, prepared as described in U.S. Pat. No. 3,516,997, and contained ina stirred mixture of 25 ml. of water and 25 ml. of acetone is added 3 g.of sodium bicarbonate. The mixture is chilled to -10° C. and 2.2 g. ofbromoacetyl bromide in one ml. of acetone is slowly added to the stirredmixture over a period of 10 minutes. The mixture is stirred for anadditional hour at -10° C. and permitted to come to room temperature.The reaction mixture is extracted with ethyl acetate and the organicphase is discarded. The aqueous phase is layered with 100 ml. of ethylacetate and the aqueous phase adjusted to a pH of 2 with a 40% solutionof phosphoric acid. The organic phase is separated, dried over sodiumsulfate and decolorized with charcoal. The solution is filtered,evaporated and the residue is triturated with ether. The residue isdried in vacuo to yield 0.7 g of7-(α-bromoacetylamino)-3-[(5-methyl-1,3,4-thiadiazol-2-ylthio)methyl]decephalosporanicacid.

Following essentially the same procedure and substituting7-amino-7-methoxy-3-[(5-methyl-1,3,4-thiadiazol-2-ylthio)methyl]decephalosporanicacid,7-amino-3-[(1-methyl-1,2,3,4-tetrazol-5-ylthio)methyl]decephalosporanicacid and7-amino-7-methoxy-3-[(1-methyl-1,2,3,4-tetrazol-5-ylthio)methyl]decephalosporanicacid for the7-amino-3-[(5-methyl-1,3,4-thiadiazol-2-ylthio)methyl]decephalosporanicacid above results in the formation of7-(α-bromoacetylamino)-7-methoxy-3-[(5-methyl-1,3,4-thiadiazol-2-ylthio)methyl]decephalosporanicacid,7-(α-bromoacetylamino)-3[(1-methyl-1,2,3,4-tetrazol-5-ylthio)methyl]decephalosporanicacid, and7-(α-bromoacetylamino)-7-methoxy-3-[(1-methyl-1,2,3,4-tetrazol-5-ylthio)methyl]decephalosporanicacid, respectively.

EXAMPLE 127-[2-(4-Oxo-1-pyridinyl)acetylamino]-3-[(5-methyl-1,3,4-thiadiazol-2-ylthio)methyl]decephalosporanicacid, sodium salt

To 4.65 g. of7-(α-bromoacetylamino)-3-[(5-methyl-1,3,4-thiadiazol-2-ylthio)methyl]decephalosporanic,as prepared in Example 11, is added 50 ml. of chloroform and 5 ml. ofN,O-bis(trimethylsily)acetamide. The mixture is stirred under anatmosphere of nitrogen until a clear solution is obtained,4-trimethylsilyloxypyridine (1.6g.) is added and the mixture stirred for18 hours under nitrogen. Methyl alcohol (5 ml.) is added and the solidprecipitate which forms is collected via filtration. The precipitate isdissolved in 100 ml. of methyl alcohol, 5 ml. of a 2 N sodium2-ethylhexanoate solution in n-butanol is added, followed by 200 ml. ofether. The precipitate which forms is collected via filtration and driedunder vacuum to yield the sodium salt of7-[2-(4-oxo-1-pyridinyl)acetylamino]-3-[(5-methyl-1,3,4-thiadiazol-2-ylthio)methyl]decephalosporanicacid.

Following essentially the same procedure but substituting7-(α-bromoacetylamino)-7-methoxy-3-[(5-methyl-1,3,4-thiadiazol-2-ylthio)methyl]decephalosporanicacid,7-(α-bromoacetylamino)-3-[(1-methyl-1,2,3,4-tetrazol-5-ylthio)methyl]decephalosporanicacid or7-(α-bromoacetylamino)-7-methoxy-3-[(1-methyl-1,2,3,4-tetrazol-5-ylthio)methyl]-decephalosporanicacid for the7-(α-bromoacetylamino)-3-[(5-methyl-1,3,4-thiadiazol-2-ylthio)methyl]decephalosporanicacid above results in the formation of the sodium salts of7-methoxy-7-[2-(4-oxo-1-pyridinyl)acetylamino]-3-[(5-methyl-1,3,4-thiadiazol-2-ylthio)methyl]decephalosporanicacid,7-[2-(4-oxo-1-pyridinyl)acetylamino]-3-[(1-methyl-1,2,3,4-tetrazol-2-ylthio)methyl]decephalosporanicacid, and7-methoxy-7-[2-(4-oxo-1-pyridinyl)acetylamino]-3-[(1-methyl-1,2,3,4-tetrazol-2-ylthio)methyl]decephalosporanicacid, respectively.

EXAMPLE 137-[2-(3-cyano-4-oxo-1-pyridinyl)acetylamino]-3-[(5-methyl-1,3,4-thiadiazol-2-ylthio)methyl]decephalosporanic acid, sodium salt

To a chloroform solution of7-(α-bromoacetylamino)-3-[(5-methyl-1,3,4-thiadiazol-2-ylthio)methyl]decephalosporanicacid and N,N-diethylaniline is added one equivalent of3-cyano-4-trimethylsilyloxypyridine. The mixture is stirred forapproximately 15 hours at room temperature under an atmosphere ofnitrogen. Methyl alcohol is added followed by the addition of anhydrousether. The precipitate which forms is removed by filtration, dissolvedin methyl alcohol and an equivalent amount of a solution of 2-N-sodium2-ethylhexanoate in butanol added thereto. An equal volume of ether isadded and the precipitate which forms is removed by filtration and driedunder vacuum to yield7-[2-(3-cyano-4-oxo-1-pyridinyl)acetylamino]-3-[(5-methyl-1,3,4-thiadiazol-2-ylthio)methyl]decephalosporanicacid as the sodium salt.

EXAMPLE 147-Methoxy-7-[2-(4-oxo-1-quinolinyl)acetylamino]-3-[(1-methyl-1,2,3,4-tetrazol-5-ylthio)methyl]decephalosporanic acid, sodium salt

A mixture of sodium7-methoxy-7-[2-(4-oxo-1-quinolinyl)acetylamino]cephalosporanate (3.5g.), sodium bicarbonate (2.5 g.), 1-methyl-5-mercapto-1,2,3,4-tetrazole(2.6 g.), and 60 ml. of water is heated at about 70° C. under anatmosphere of nitrogen for about 4 hours. The reaction mixture is cooledand evaporated under reduced pressure. The residue which remains istriturated with acetone, dissolved in methanol and filtered. Isopropylalcohol is added to the filtrate to form a precipitate, which iscollected by filtration and vacuum dried to yield a precipitate of7-methoxy-7-[2-(4-oxo-1-quinolinyl)acetylamino]-3-[(1-methyl-1,2,3,4-tetrazol-5-ylthio)methyl]decephalosporanic acid as the sodium salt.

Following essentially the same procedure but substituting7-[2-(4-oxo-1-pyridinyl)acetylamino]cephalosporanic acid or7-[2-methyl-2-(2,6-dimethyl-4-oxo-1-pyridinyl)acetylamino]cephalosporanicacid results in the formation of7-[2-(4-oxo-1-pyridinyl)acetylamino]-3-[(1-methyl-1,2,3,4-tetrazol-5-ylthio)methyl]decephalosporanicacid and7-[2-methyl-2-(2,6-dimethyl-4-oxo-1-pyridinyl)acetylamino]-3-[(1-methyl-1,2,3,4-tetrazol-5-ylthio)methyl]decephalosporanicacid as their sodium salts, respectively.

EXAMPLE 157-[2-(4-oxo-1-pyridinyl)acetylamino]-3-[(5-methyl-1,3,4-thiadiazol-2-ylthio)methyl]decephalosporanicacid, sodium salt

To a solution of (5 g.) of sodium7-[2-(4-oxo-1-pyridinyl)acetylamino]cephalosporanate in 500 ml. of wateris added (0.95 g.) of sodium bicarbonate and (2.96 g.) of2-mercapto-5-methyl-1,3,4-thiadiazole. The mixture is heated under anitrogen atmosphere at 70° C. for 3 hours and evaporated under reducedpressure. The residue is dissolved in 50 ml. of methanol and treatedwith an excess of acetonitrile. The white precipitate which forms isremoved by filtration, washed with acetonitrile and dried under vacuumto yield (4.3 g.) 7-[2-(4-oxo-1-pyridinyl)acetylamino]-3-[(5-methyl-1,3,4-thiadiazol-2-ylthio)methyl]decephalosporanic acid as the sodium salt.

Following essentially the same procedure but substituting the sodiumsalts of 7-methoxy-7-[2-(4-oxo-1-quinolinyl)acetylamino]cephalosporanicacid, 7-methoxy-7-[2-(4-oxo-1-pyridinyl)acetylamino]cephalosporanic acidor7-[2-methyl-2-(2,6-dimethyl-4-oxo-1-pyridinyl)acetylamino]cephalosporanicacid results in the formation of7-methoxy-7-[2-(4-oxo-1-quinolinyl)acetylamino]-3-[(5-methyl-1,3,4-thiadiazol-2-ylthio)methyl]decephalosporanicacid,7-methoxy-7-[2-(4-oxo-1-pyridinyl)acetylamino]-3-[(5-methyl-1,3,4-thiadiazol-2-ylthio)methyl]decephalosporanicacid or7-[2-methyl-2-(2,6-dimethyl-4-oxo-1-pyridinyl)acetylamino]-3-[(5-methyl-1,3,4-thiadiazol-2-ylthio)methyl]decephalosporanicacid as their sodium salts, respectively.

EXAMPLE 16 Pivaloyloxymethyl 7-[2-(4-oxo-1-pyridinyl)acetylamino]cephalosporanate

To (4.5 g.) of sodium7-[2-(4-oxo-1-pyridinyl)acetylamino]cephalosporanate dissolved in 40 ml.of dimethylformamide and chilled to 0° C. is added (2.6 g.) ofpivaloyloxymethyliodide and the solution stirred for approximately 25minutes. The mixture is diluted with ethyl acetate (170 ml.), washedwell with water and then washed with a dilute solution of sodiumbicarbonate. The organic phase is dried over anhydrous sodium sulfate,filtered and evaporated to dryness to yield pivaloyloxymethyl7-[2-(4-oxo-1-pyridinyl)acetylamino]cephalosporanate.

Following essentially the same procedure but substitutingacetoxymethyliodide, N-chloromethyl-N-methylurethane, orp-acetoxybenzylbromide for the pivaloyloxymethyliodide above results inthe formation of acetoxymethyl7-[2-(4-oxo-1-pyridinyl)acetylamino]cephalosporanate,N-ethoxycarbonyl-N-methylaminomethyl7-[2-(4-oxo-1-pyridinyl)acetylamino]cephalosporanate andp-acetyloxybenzyl 7-[2-(4-oxo-1-pyridinyl)acetylamino]cephalosporanate,respectively.

Substituting the sodium salts of7-methoxy-7-[2-(4-oxo-1-pyridinyl)acetylamino]-3-[(1-methyl-1,2,3,4-tetrazol-5-ylthio)methyl]decephalosporanicacid, 6-methoxy-6-[2-(3-cyano-4-oxo-1-pyridinyl)acetylamino]penicillanicacid or 6-[2-(4-oxo-1-quinolinyl)-2-methylacetylamino]-penicillanic acidfor the 7-[2-(4-oxo-1-pyridinyl)acetylamino]cephalosporanic acid aboveresults in the formation of pivaloyloxymethyl7-methoxy-7-[2-(4-oxo-1-pyridinyl)acetylamino]-3-[(1-methyl-1,2,3,4-tetrazol-5-ylthio)methyl]decephalosporanate,pivaloyloxymethyl6-methoxy-6[2-(3-cyano-4-oxo-1-pyridinyl)acetylamino]pencillanate andpivaloyloxymethyl6-[2-(4-oxo-1-quinolinyl)-2-methylacetylamino]penicillanate,respectively.

EXAMPLE 17 N-Ethoxycarbonyl-N-methylamino methyl7-[2-(4-oxo-1-pyridinyl)acetylamino]-3-[(5-methyl-1,3,4-thiadiazol-2-ylthio)methyl]decephalosporanate

To a slurry of sodium7-[2-(4-oxo-1-pyridinyl)acetylamino]-3-[(5-methyl-1,3,4-thiadiazol-2-ylthio)methyl]decephalosporanate(0.01 mole) contained in 20 ml. of dimethylformamide and maintained at atemperature of 0°-5° C. is added a solution ofN-chloromethyl-N-methylurethane (0.01 mole) contained in 5 ml. ofdimethylformamide. The mixture is stirred for about one hour and pouredinto water. The precipitate which forms is dissolved in ethyl acetate,washed with water followed by a dilute solution of sodium bicarbonateand dried over magnesium sulfate. The solution is evaporated underreduced pressure to yield the desiredN-ethoxycarbonyl-N-methylamino-methyl7-[2-(4-oxo-1-pyridinyl)acetylamino]-3-[(5-methyl-1,3,4-thiadiazol-2-ylthio)methyl]decephalosporanate.

EXAMPLE 18

Specific nutrient agar plates are completely innoculated with thevarious test organisms. Filter paper discs are placed on the surface ofthe agar and wetted with 0.1 ml. of a solution containing 10, 100 and1,000 micrograms of the test compound. Zones of inhibition of microbialgrowth are used to indicate the antibacterial activity of the testcompound against the various test organisms employed.

The following table summarizes the in vitro activity of the followingrepresentative compounds:6-[2-(4-oxo-1-pyridinyl)acetylamino]penicillanic acid, sodium salt (1),7-[2-(4-oxo-1-pyridinyl)acetylamino]desacetoxycephalosporanic acid (2),6-[2-(3,5-diioso-4-oxo-1-pyridinyl)acetylamino]penicillanic acid, sodiumsalt (3), 7-[2-(4-oxo-1-pyridinyl)acetylamino]cephalosporanic acid,sodium salt (4) and 6-[2-(4-oxo-1-quinolinyl)acetylamino]penicillanicacid, sodium salt (5).

    __________________________________________________________________________    MINIMAL INHIBITING CONCENTRATION (mcg/ml)                                                                  (Penicillinase                                                                Producing)                                             Staphylococcus                                                                        Salmonella                                                                            Streptococcus                                                                        Staphylococcus                                                                        Acid                                     Compound                                                                            aureus  schottmuelleri                                                                        pyogenes                                                                             aureus  Resistance                               __________________________________________________________________________    (1)   10      100     1,000  1,000   Yes                                      (2)   1,000   >1,000  1,000  >1,000  Yes                                      (3)   10      100     >1,000 >1,000  Yes                                      (4)   10      100       100  1,000   Yes                                      (5)   10      100     1,000  1,000   Yes                                      __________________________________________________________________________

We claim:
 1. A 7-[(4-oxo-1-pyridinyl)acetylamino]cephalosporinderivative having the formula: ##STR20## wherein R₁, R₂, R₃ and R₄ areeach selected from the group consisting of hydrogen, halogen, loweralkylhaving from 1 to 4 carbon atoms, trifluoromethyl, carboxy, carbomethoxy,carbethoxy and when R₁ is taken in combination with R₂ forms the cyclicradical --CH₂ CH₂ CH₂ CH₂ -- and --CH═CH--CH═CH--;R₅ is selected fromthe group consisting of hydrogen, methyl, carboxy, carbomethoxy andcarbethoxy; X is selected from the group consisting of hydrogen,hydroxy, acetoxy and N-pyridinium; R₇ is selected from the groupconsisting of hydrogen, alkanoyloxymethyl, alkanoylaminomethyl,alkoxycarbonylaminomethyl and p-(alkanoyloxy)benzyl in which thealkanoyl or alkoxy group contains from 1 to 5 carbon atoms; R₈ ishydrogen or methoxy; andthe pharmaceutically acceptable salts thereof.2. A compound according to claim 1 wherein R₈ is hydrogen.
 3. A compoundaccording to claim 1, wherein R₈ is methoxy.
 4. A compound according toclaim 1, wherein R₅ is hydrogen.
 5. A compound of claim 1, which is7[2-(4-oxo-1-pyridinyl)acetylamino]cephalosporanic acid and thepharmaceutically acceptable salts thereof.
 6. A compound of claim 1,which is 7-[2-(4-oxo-pyridinyl)acetylamino]desacetoxycephalosporanicacid and the pharmaceutically acceptable salts thereof.
 7. A compound ofclaim 1, which is7-[2-(2,6-dimethyl-4-oxo-1-pyridinyl)acetylamino]desacetoxycephalosporanicacid.